This invention relates to rotor blades in wind turbines.
An aileron is one of several adjustable portions on the trailing edge of an airplane wing. Ailerons, spoilers, and flaps are employed to provide control surfaces to manipulate the flight of the airplane. Each of these devices is used on the aircraft in particular situations. Typically, ailerons are deployed through small angles to provide turning and rolling forces. Flaps are extended and lowered during takeoffs and landings to increase the wing surface area and to alter the lift of the wing.
Ailerons have also been investigated for use on rotor blades used on wind turbines. While there are some similarities between an aircraft wing and a rotor blade and some similar terminology is used, the rotor blade and the forces acting on the rotor blade are much different from the aircraft wing. An airplane is subject to two sets of opposing forces: gravity, lift, thrust, and drag. The adjustable ailerons, spoilers, and flaps, which change the relative pressure around the fixed position wing, are used to control motion vertically and in the direction of flight.
A rotor blade also has lift and drag characteristics, but the rotor does not have engines to provide thrust, and gravity acts much differently on a wind turbine rotor blade since a blade rotates in a plane nearly perpendicular to the ground. Since the blade rotates at a significant speed, centripetal acceleration is much greater than gravitational forces. Furthermore, due to the rotation, there are also other mechanical problems and twisting forces which are different from forces experienced by the fixed wing of an aircraft.
On a rotor blade, the aileron affects rotor torque and speed. This method of rotor control can be used as an alterative to blade pitch control, either full span or partial span. Ailerons have also been used in wind turbines as an alternative to tip drag brakes.